Can't change default storage from SD to Phone?

I have a BLU vivo XL, and I have a micro SD card into it to expand my storage, but it has been downloading everything onto that SD card and now its full, I still have space on my phone but it won't install anything to the phone, only the SD card...Please Help. I have taken the SD card out and then installed stuff and it worked. But I can't change the default storage.

I have a special key for my Blu Vivo xl 2 and it opens the sim as well as the micro sd card slots it should com in your case. Also I a good way to transfer the partial information to your new phone is essential to not losing too much room as a confused waste in your phone's storage. Download an app if need be in the google play store.